Thermal actuator with reduced temperature extreme and method of operating same
First Claim
1. A thermal actuator for a micro-electromechanical device comprising:
- (a) abase element;
(b) a cantilevered element extending from the base element and residing at a first position, the cantilevered element including a first layer constructed of an electrically resistive material patterned to have a first resistor segment and a second resistor segment each extending from the base element, a coupling device that conducts electrical current serially between the first and second resistor segments, and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer; and
(c) a first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density in the first and second resistor segments and a power density maximum within the coupling device resulting in a deflection of the cantilevered element to a second position and wherein the power density maximum is less than four times the activation power density.
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Abstract
An apparatus for a thermal actuator for a micromechanical device, especially a liquid drop emitter such as an ink jet printhead, is disclosed. The disclosed thermal actuator comprises a base element and a cantilevered element extending from the base element and normally residing at a first position before activation. The cantilevered element includes a first layer constructed of an electrically resistive material, such as titanium aluminide, patterned to have a first resistor segment and a second resistor segment each extending from the base element; a coupling device that conducts electrical current serially between the first and second resistor segments; and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer. A first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment are provided to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density in the first and second resistor segments and a power density maximum within the coupling device resulting in a deflection of the cantilevered element to a second position and wherein the power density maximum is less than four times the activation power density. The coupling device may be formed as a segment in the first layer or in a third layer of an electrically active material. Methods of operating a liquid drop emitter having a thermal actuator are disclosed which avoid the generation of vapor bubbles.
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Citations
26 Claims
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1. A thermal actuator for a micro-electromechanical device comprising:
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(a) abase element;
(b) a cantilevered element extending from the base element and residing at a first position, the cantilevered element including a first layer constructed of an electrically resistive material patterned to have a first resistor segment and a second resistor segment each extending from the base element, a coupling device that conducts electrical current serially between the first and second resistor segments, and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer; and
(c) a first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density in the first and second resistor segments and a power density maximum within the coupling device resulting in a deflection of the cantilevered element to a second position and wherein the power density maximum is less than four times the activation power density. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A thermal actuator for a micro-electromechanical device comprising:
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(a) a base element;
(b) a cantilevered element extending from the base element and residing at a first position, the cantilevered element including a first layer constructed of an electrically resistive material, a first resistor segment and a second resistor segment each extending from the base element and patterned in the electrically resistive material, a coupling segment that conducts current serially between the first and second resistor segments patterned in the electrically resistive material, and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer; and
(c) a first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density in the first and second resistor segments and a power density maximum within the coupling device resulting in a deflection of the cantilevered element to a second position and wherein the power density maximum is less than four times the activation power density. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A liquid drop emitter comprising:
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(a) a chamber, formed in a substrate, filled with a liquid and having a nozzle for emitting drops of the liquid;
(b) a thermal actuator having a cantilevered element extending a from a wall of the chamber and a free end residing in a first position proximate to the nozzle, the cantilevered element including a first layer constructed of an electrically resistive material patterned to have a first resistor segment and a second resistor segment each extending from the wall, a coupling device that conducts current serially between the first and second resistor segments, and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer; and
(c) a first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density within the first and second resistor segments and a power density maximum within the coupling device, resulting in rapid deflection of the cantilevered element and ejection of a liquid drop, wherein the power density maximum is less than four times the activation power density. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A liquid drop emitter for a micro-electromechanical device comprising:
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(a) a chamber, formed in a substrate, filled with a liquid and having a nozzle for emitting drops of the liquid;
(b) a thermal actuator having a cantilevered element extending a from a wall of the chamber and a free end residing in a first position proximate to the nozzle, the cantilevered element including a first layer constructed of an electrically resistive material patterned to have a first resistor segment and a second resistor segment each extending from the wall, a coupling segment that conducts current serially between the first and second resistor segments patterned in the electrically resistive material, and a second layer constructed of a dielectric material having a low coefficient of thermal expansion and attached to the first layer; and
(c) a first electrode connected to the first resistor segment and a second electrode connected to the second resistor segment to apply an electrical voltage pulse between the first and second electrodes thereby causing an activation power density within the first and second resistor segments and a power density maximum within the coupling device, resulting in rapid deflection of the cantilevered element and ejection of a liquid drop, wherein the power density maximum is less than four times the activation power density. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification